"...This non-elliptic crypto algorithm is based on prime numbers. It is probably the most used algorithm used today. When generating keys with less then 2048-bits it is also considered insecure. The problem with RSA is it's source of entropy that is causing the weakest link. This is probable the first algorithm to fall when quantum computations will get more mature. Using a keysize of 3072-bit you should be safe for the upcoming 2 years, whereas the 4096-bit keys should probably put you on the safe side for at least the next 5 years...." - https://marcofranssen.nl/upgrade-your-ssh-security